Normally clang avoids creating expressions when it encounters semantic
errors, even if the parser knows which expression to produce.
This works well for the compiler. However, this is not ideal for
source-level tools that have to deal with broken code, e.g. clangd is
not able to provide navigation features even for names that compiler
knows how to resolve.
The new RecoveryExpr aims to capture the minimal set of information
useful for the tools that need to deal with incorrect code:
source range of the expression being dropped,
subexpressions of the expression.
We aim to make constructing RecoveryExprs as simple as possible to
ensure writing code to avoid dropping expressions is easy.
Producing RecoveryExprs can result in new code paths being taken in the
frontend. In particular, clang can produce some new diagnostics now and
we aim to suppress bogus ones based on Expr::containsErrors.
We deliberately produce RecoveryExprs only in the parser for now to
minimize the code affected by this patch. Producing RecoveryExprs in
Sema potentially allows to preserve more information (e.g. type of an
expression), but also results in more code being affected. E.g.
SFINAE checks will have to take presence of RecoveryExprs into account.
Initial implementation only works in C++ mode, as it relies on compiler
postponing diagnostics on dependent expressions. C and ObjC often do not
do this, so they require more work to make sure we do not produce too
many bogus diagnostics on the new expressions.
See documentation of RecoveryExpr for more details.
original patch from Ilya
This change is based on https://reviews.llvm.org/D61722
Reviewers: sammccall, rsmith
Reviewed By: sammccall, rsmith
Tags: #clang
Differential Revision: https://reviews.llvm.org/D69330
Summary:
The expected pattern is for subclasses to initialize through
computeDependence, which needs only setDependence.
The few places that still use addDependence can be simulated with get+set.
Reviewers: hokein
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D76392
The only subexpression that is considered an error now is TypoExpr, but
we plan to add expressions with errors to improve editor tooling on broken
code. We intend to use the same mechanism to guard against spurious
diagnostics on those as well.
See the follow-up revision for an actual usage of the flag.
Original patch from Ilya.
Reviewers: sammccall
Reviewed By: sammccall
Tags: #clang
Differential Revision: https://reviews.llvm.org/D65591
To group the code in one place, simplify it and make it easier to add
the containsErrors bit and find existing bugs.
Reviewers: sammccall
Reviewed By: sammccall
Tags: #clang
Differential Revision: https://reviews.llvm.org/D73638
Sam McCall